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Sash window guide

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Sash windows are strongly associated with Victorian and Georgian properties, but they still remain popular today. Rather than swinging outwards like casement styles, sash windows are opened by sliding them vertically (or sometimes horizontally).

While generally seen in older buildings, modern sash windows can suit a wide range of properties, offering a unique balance between historic charm and modern technical performance. Plus, their enduring popularity means they come in various styles, materials and finishes, catering to every homeowner’s taste and budget.

Our comprehensive guide to sash windows will equip you with everything you need to know about them, including materials, glazing options, average windows prices and factors to consider before collecting quotes.

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What is a sash window?

There’s no real consensus on when sash windows were first used, but most believe they originated in 17th-century Britain. Sash windows were particularly prevalent throughout the Georgian period (1714-1837) and Victorian period (1837-1901). 

Unlike casement windows, sash windows were designed to open vertically, meaning they wouldn’t touch other windows when opened across the narrow city streets typical in London and other European cities. This helped to prevent the risk of fire spreading from one building to another. 

Over the centuries, the sash window has evolved, yet it still retains its core historical characteristics and charm.

At its most basic, a sash window consists of one or more movable panels called window sashes. These sashes form the framework that holds the panes of glass. This distinctive design element differentiates sash windows from other types of windows.

Less commonly, sash windows can also slide horizontally. These are sometimes known as “Yorkshire sliders”, “Yorkshire lights”, or simply “sliders”. 

Modern sash windows are valued for their timeless aesthetics. While usually associated with period properties, they suit various architectural styles.

How do sash windows work?

Sash windows combine practical functionality with classic aesthetics. 

Most sash windows consist of two panels – the sashes – that slide vertically or, in some cases, horizontally within a frame.

Each sash is a unit that holds separate glass panes, usually divided by thin wooden bars called muntins. The sashes fit into vertical grooves or tracks in the frame and can slide up and down (or side to side in the case of horizontally sliding sash windows), overlapping slightly with each other when closed.

One of the most common sash window designs is the double-hung window, which allows you to open both the top and bottom sashes. You can open the bottom sash to allow cool air in, the top sash to let warm air out, or both for maximum ventilation.

The mechanics behind the sliding operation of the sashes lie in the counterbalance system, typically involving concealed cords, weights and pulleys.

Here’s how it works:

  • Traditionally, a strong cord connects each sash to a heavy counterweight
  • The counterweight, usually made from lead or cast iron, is hidden within a box frame and is perfectly balanced with the weight of the sash
  • The counterweight balance holds the sashes’ positions when opened so you can lift and drop them smoothly
  • Some modern sash windows replace the traditional counterbalance system with spring-loaded mechanisms or spiral balances, which provide the same functionality but are easier to manufacture and maintain

Sash window styles

Although restoring original sash windows is always preferable, when replacing try to replicate the original style of the sash windows. For instance, Georgian homes typically use six-over-six styles (pictured) while in Victorian houses we tend to see one-over-one. (Adobe)

Different styles of sash windows share the same core opening and closing functionality, but there are a few styles to be aware of.  

Single-hung sash windows

One of the oldest styles of sash windows, single-hung windows feature one operable sash – usually the bottom one – while the top one remains fixed. 

Modern sash windows rarely come with single-hung mechanisms, unless they’re very small. 

Double-hung sash windows

Probably the most common style of sash window today, double-hung sash windows comprise two operable sashes at the top and bottom of the window. 

This design allows for enhanced ventilation, as you can open both the upper and lower windows simultaneously. 

Horizontally sliding sash windows

Also known as Yorkshire light or Yorkshire slider windows, horizontally sliding sash windows include sashes that move sideways rather than up and down. 

While less common, this style is perfect for spaces with wide window apertures but limited vertical height that can’t accommodate full-length sash windows. 

Triple-sash sash windows

Larger properties can accommodate triple-sash windows, which comprise three sashes. These are most common in stately homes and historical properties, but are a rare find in modern times.

Sash window materials

You’ll find sash windows built from all typical window frame materials, including unplasticized polyvinyl chloride (uPVC), aluminium, composite and wood. Wood perfectly suits the style and aesthetic of sash windows, but aluminium, composite and uPVC offer modern alternatives. 

Wood

Wood is the most authentic choice for sash windows. Not only does it offer a splendid finish, but it also delivers excellent technical specifications with great natural insulation, helping to keep your home warm in winter and cool in summer.

The two main types of timber used in sash window construction are softwoods and hardwoods. 

Softwoods, such as pine, spruce and fir, are cheaper and more flexible. Conversely, hardwoods, such as oak and mahogany, are denser and more durable but are nearly always more expensive than softwoods. Additionally, modern sash windows are sometimes constructed from layers of wood rather than solid pieces, which is also known as engineered wood. 

Wooden windows require regular maintenance, including painting or staining, to maintain their longevity. However, with proper upkeep, high-quality wooden sash windows can last for decades. 

uPVC

Modern sash windows are also constructed from uPVC. These windows are generally more affordable than their wooden counterparts, blending classic aesthetics with modern synthetic materials. 

uPVC windows offer excellent thermal efficiency and come in a wide range of finishes, including a woodgrain effect, allowing you to achieve the traditional look of wood without the price tag. Despite being plastic, uPVC can be recycled up to 10 times, making it a somewhat environmentally friendly material. 

Aluminium

Aluminium windows offer a sleek, modern aesthetic, combining the classic style of sash windows with cutting-edge materials. They’re incredibly durable and resistant to weathering, requiring very little maintenance.

Moreover, since aluminium is a stronger material than wood or uPVC, the frames are thinner, which maximises the area covered by glass. Aluminium is a high-end alternative to wood for modern properties. 

Composite

Composite sash windows typically combine timber and aluminium frames, providing the natural beauty and insulation properties of wood on the inside with the durability, strength and low maintenance of aluminium on the outside.

Composite windows offer superior thermal efficiency, excellent durability and various design options. They’re among the most expensive window frame options.

Sash window finish options

Sash windows come in a wide variety of finishes to match any property style. 

Below, we’ll explore the most common finishes for uPVC, aluminium, wood and composite sash windows.

uPVC sash window finishes

While uPVC is often thought of as being white, contemporary uPVC windows are available in a multitude of finishes:

  • White: as the traditional finish for uPVC windows, plain white is a versatile choice that fits seamlessly with most properties
  • Woodgrain effect: this finish imitates the look of natural wood, fusing classic aesthetics with modern materials
  • Colour: modern uPVC windows can come in almost any colour, including unusual reds and blues, cool greys and greens, and earth tones, such as beige, but coloured uPVC windows tend to be more expensive than plain white

Aluminium sash window finishes

Aluminium sash windows also come in multiple finishes and are relatively straightforward to paint or spray, providing almost total creative control.

  • Powder coating: this is the most common finish for aluminium windows. Powder coatings cover a vast colour palette and are highly resistant to weathering, scratches and corrosion
  • Anodised finish: anodising enhances the metallic sheen of aluminium and increases its corrosion resistance, delivering a contemporary look

Wooden sash window finishes

Wooden sash windows can look timeless and authentic, which makes this finish the go-to for contemporary sash window design.

  • Painting: painting wood is straightforward and allows you to tailor your windows to your home’s colour scheme
  • Staining: staining lets the woods’ natural grain shine, creating a warm, traditional aesthetic
  • Clear varnishing: clear varnish retains the natural look of wood while offering some protection from the elements

Composite sash window finishes

Composite sash windows merge the strengths of two materials – usually weather-resistant uPVC or aluminium on the exterior and aesthetic wood on the interior. You can achieve a variety of finishes on this type of sash window.

  • Dual-colour finish: composite sash windows can have different finishes on the inside and outside. For example, you might opt for a durable coloured finish for the exterior and a natural wood finish for the interior
  • Woodgrain effect: like uPVC, composite windows can mimic the appearance of natural wood. This offers an appealing balance between the aesthetic appeal of wood and the durability of modern materials

Sash window glazing options

If your sash windows are beyond repair and require replacing, double, or even triple, glazing will improve energy efficiency and noise reduction. (Adobe)

Sash windows can be fitted with any typical exterior glazing, such as double glazing, triple glazing or low-emissivity (low-E) glass. 

While period sash windows would’ve been single glazed, the vast majority of newly fitted windows are double glazed at least. This is mandatory for new window installations in order to comply with building regulations in England and Wales. 

Here’s a comprehensive breakdown of the different types of glazing you can choose for your sash windows.

Double glazing

Double-glazed windows comprise two panes of glass with an inert, gas-filled space in between. This window type has become the standard in much of the UK since building regulations essentially limited single glazing for new window installations in April 2002.

Around 18 per cent of a home’s heat is lost through its windows. By effectively reducing heat loss, modern double glazing typically achieves a window energy rating (WER) of A or above from the British Fenestration Rating Council (BFRC).

Alongside their energy efficiency benefits, double-glazed windows provide excellent sound insulation and improved security compared with single-glazed windows. 

Triple glazing

Triple-glazed windows incorporate three panes of glass, each separated by an inert, gas-filled cavity. 

This significantly reduces heat transfer, making triple-glazed windows more energy-efficient than their double-glazed counterparts.

Due to their additional insulation layer, triple-glazed windows can achieve BFRC ratings of A+ or higher, making them perfect for homeowners who prioritise energy efficiency. 

Triple-glazed windows also reduce noise due to their additional glass pane, so they’re particularly beneficial for homes in busy areas or near high-traffic roads. 

While the upfront cost of triple-glazed windows is often higher than other options, they can reduce energy bills over time, particularly when paired with high-quality insulative window frames. 

Low-E glass

Low-E glass features a microscopically thin, transparent coating that reflects heat back into your home while allowing natural light to enter. 

This type of glass significantly improves the energy efficiency of windows and is especially effective when coupled with double or triple glazing.

The coated pane faces the home’s interior, reflecting heat into the room. Low-E glass also helps to keep your home cool in the summer by preventing solar radiation from heating the interior of your home – perfect for properties that tend to get overly warm. 

Triple-glazed low-E windows often achieve a BFRC rating of A++, the highest available rating.

Sash windows and planning law

In certain circumstances, you may be required to install sash windows, such as if you’re refurbishing a listed building or a property in a conservation area. Planning authorities may stipulate that you need to install windows that correspond to the original structure or look similar to those of other local properties.

In some cases, this might involve replacing sash windows with a matching style. For example, there are numerous conservation zones in London in which you’ll be required to replace a sash window with another sash window, rather than another type, such as casements. 

In London, sash windows are characteristic of Georgian and Victorian flats and terraces. In some cases, you may be asked to replace your Victorian and Georgian sash windows with the exact material and finish that was originally used – likely wood. 

There are two main situations in which you may need to consider your window choice:

  • Listed buildings: modifications to buildings labelled as “listed” by heritage organisations are stringently controlled. Different organisations compile lists of such buildings across the UK. If you’re changing the windows in a listed building, you’ll probably be required to retain the original style and materials, which may include sash windows
  • Conservation areas: similarly, if your property is situated within a conservation area, it may be necessary to fit windows in line with others in the vicinity to help preserve the historical character of the area. This may pertain to both the window’s materials and style

If you’re uncertain as to whether these conditions apply to your project, consult a professional, such as a surveyor. Conducting work on a listed building without obtaining the necessary permissions is a criminal offence, and you might be ordered to undo any modifications. 

Likewise, embarking on an extension or renovation project without proper planning permission or a lawful development certificate is risky. It could lead to fines or legal action from the local council and complicate any plans to sell your home.

How much do sash windows cost?

Various factors can influence the total cost of sash windows, including the windows’ dimensions, the materials chosen for their construction, the type of glazing and the specific hardware and fittings used. 

Here’s a more detailed breakdown. Prices include installation, but are intended to be a rough guide only. 

Window size

The dimensions of your sash windows will directly influence the overall cost. Naturally, larger windows require larger frames and glazing, which is likely to increase the price. 

Speciality styles, such as triple-sash windows, typically cost more than standard double sash windows. 

Materials

uPVC

uPVC sash windows are popular due to their affordability, durability and energy efficiency. 

Standard uPVC sash windows prices range from approximately £500-£1,000 per window. This wide range is due to factors such as window size, design, glazing type and the installation service rate.

Wood

Wooden sash windows provide excellent insulation and a classic, elegant appearance, but they tend to be more expensive than uPVC windows. 

Prices for wooden sash windows can start at around £1,000 and extend well beyond £2,500 per window, depending on the type of wood used, the finish, the complexity of the design and the installation costs.

Aluminium

Aluminium sash windows offer a sleek, modern look and durable construction. They’re generally more expensive than uPVC options, with prices often starting from around £700 and reaching up to £2,500 per window. 

Composite

Composite sash windows combine the best features of different materials to provide a high-quality, durable window solution. 

Composite windows can vary significantly in price, depending largely on the materials used and the complexity of the manufacturing process. They tend to range from about £1,000 to more than £3,000 per window.

Glazing options

The type of glazing you choose for your sash windows also impacts the total cost. 

While double glazing is the standard choice in the UK due to its excellent insulation and soundproofing properties, other options have become increasingly popular, such as low-E glass and triple glazing, which deliver exceptional thermal performance. 

Though the latter options may come with a higher upfront cost, they can significantly improve your home’s energy efficiency, potentially leading to savings on your energy bills over time. Other savings can be made via window replacement grants, although you must be eligible for these.

Hardware and fittings

The hardware and fittings used in your sash windows, such as the window handles, locks and pulley system for the sashes, also contribute to the overall cost. 

High-quality, multi-point locking systems are generally more expensive than simpler, single-lock systems. 

Similarly, window handles vary in price depending on the design and the materials used. 

The type of counterweight system (cord, chain or spring loaded) can also influence the cost, with traditional cord-and-weight systems typically being cheaper than modern, spring-loaded variants.

Sash window pros and cons

Sash windows have been popular for almost 300 years. However, they’re not without some drawbacks. 

Here’s a detailed breakdown of the pros and cons of sash windows.

Pros

Aesthetic appeal

Sash windows are renowned for their aesthetic appeal and timeless charm. They add an element of classic elegance to a property that few other window styles can match. 

Their distinctive vertical sliding design is often associated with Georgian and Victorian architecture, making them the window of choice for those wishing to maintain the period character of their property or create a traditional look in a newer home. 

Excellent ventilation

Sash windows offer versatile ventilation options. Since they’re usually designed to open at both the top and the bottom, they can create an efficient cooling convection airflow. 

Warm air rises and escapes from the top opening, while cooler air enters through the bottom, helping to maintain a comfortable temperature inside the building.

Compatibility with various architectural styles

Sash windows are not just for Georgian- and Victorian-style homes. 

Their elegant design can blend seamlessly with most architectural styles, from period properties to contemporary homes. This versatility makes them an attractive option for many homeowners and architects.

Listed buildings and homes in conservation areas might be required to maintain the local aesthetic by replacing like-for-like sash windows. Always check with your local authority to obtain the correct permissions. (Adobe)

Cons

High initial cost

Traditional timber sash windows can be more expensive than other window types, such as uPVC or standard casement windows. 

It’s important to note that despite the higher initial cost, sash windows can add value to your property, which may offset the upfront expense.

Maintenance requirements

Wooden sash windows require regular maintenance to keep them looking their best and prevent rot, swelling and distortion. 

Maintenance typically involves periodic painting or staining to protect the wood from the elements. However, modern materials, such as uPVC and aluminium, offer the traditional look of sash windows with reduced maintenance needs.

Thermal efficiency concerns

Original single-glazed sash windows are often less energy efficient than their modern, double-glazed counterparts. They can be draughty and cause heat loss during the colder months. 

However, virtually all replacement sash windows are double-glazed at least. Modern sash windows are designed to provide improved thermal efficiency while maintaining the aesthetic appeal of traditional sash windows.

What to look for in a sash window quote

Before you begin hunting for sash window quotes, it’s a good idea to have a handle on precisely what you’re looking for. 

This includes the window type, frame material, glazing, hardware options and finish choices. After establishing your requirements, you can start collecting and evaluating quotes and comparing costs.

Here are some key factors to consider before collecting and comparing quotes from window companies.

Reputation

Opt for a company with an excellent track record, abundant positive reviews and a portfolio showcasing successful projects. 

If you’re interested in specialist windows, such as hardwood or composite, seek installers with expertise in those materials. 

Installers operate locally and nationally. Large national installers aren’t always the superior choice, so make sure to shop around for local quotes.

Warranty

Understanding the warranty that comes with your new sash windows is vital. 

Most reputable window installation companies in England and Wales are registered with the Fenestration Self-Assessment Scheme (FENSA).

The FENSA is a government-authorised scheme that monitors building regulation compliance for replacement windows and doors. FENSA registration confirms the installer is obligated to provide an insurance-backed warranty.

Energy efficiency

In the UK, windows are evaluated by the BFRC on a scale from A++ (the most energy efficient) to E (the least energy efficient).

A good quote clarifies the energy performance ratings of the proposed windows, which should meet or surpass current UK energy efficiency standards.

Windows with higher energy ratings may be more expensive initially, but they can save money over time by decreasing energy usage and heating costs.

Installation details

The quote should also include information about the installation process. This encompasses the projected timeline for the installation and the expected start and completion dates.

Detailed cost breakdown

A high-quality quote will always supply a detailed breakdown of costs, including the cost of the windows, materials, finishes, hardware, labour and additional costs, such as delivery fees or the disposal of old windows.

A comprehensive list will help you compare quotes accurately. Don’t hesitate to request clarification if anything in the quote is unclear.

Accreditations and certifications

Accreditations and certifications are endorsements from recognised industry bodies that confirm the competency and credibility of window installers. Certifications demonstrate that a company adheres to specific quality and performance standards.

Here are some of the key accreditations to look for:

  • The FENSA: FENSA-accredited installers are vetted regularly to guarantee they’re maintaining the standards outlined in the building regulations
  • The BFRC: as the UK’s nationally recognised scheme for rating the energy efficiency of windows, the BFRC helps consumers identify high-performing products. Look for its energy rating label on window products
  • The Glass and Glazing Federation (GGF): the GGF is a trade association representing companies that manufacture, supply or fit glass and glazing products in the UK. Member companies must adhere to a strict code of practice and high technical standards

Summary

Sash windows are a characterful, timeless choice that suit many properties. 

With their unique sliding mechanism, sash windows provide exceptional ventilation and great views. These popular windows are available in various sizes and styles, with a plethora of finishes and glazing options.

When obtaining sash window quotes, choose a reliable company with a solid reputation, positive reviews and a portfolio of successful sash window installations. 

Insurance-backed guarantees are a hallmark of trust. Seek such warranties and comprehensive quotes that detail all aspects of the project, including window materials and installation costs.

Frequently asked questions about sash windows

Aluminium, composite and uPVC sash windows require the same level of maintenance as other window styles. While traditional timber sash windows require regular maintenance to keep them in top condition, this doesn’t necessarily mean they’re high maintenance. 

Maintenance depends on several factors, such as the window’s exposure to weather conditions, the quality of the original paint job and the condition of the timber. If well-maintained, timber sash windows can last for several decades.

The cost of sash window repairs depends on the extent of the issue. Minor repairs, such as replacing broken cords or fixing a stuck window, can cost in the region of £100 to £300. 

More extensive repairs, including rot removal or full window restoration, can cost several hundred pounds per window. In some cases, particularly for severely deteriorated windows, replacing the window entirely may be more cost effective than repairing it.

The worth of sash windows is subjective. It depends on individual preferences, needs and property style. Sash windows add a classic aesthetic appeal to a property that can boost its value, particularly in period homes or conservation areas. They also provide excellent ventilation and can be more energy efficient if well maintained and fitted with high-quality glazing.

However, the initial cost of sash windows, particularly high-end styles, can be higher than other types of windows. They may also require more maintenance than casement windows or uPVC windows. 

Therefore, whether sash windows are worth it will depend on your budget, your willingness to maintain them and whether their benefits align with your property.

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Sam Jeans

Writer

Sam is an experienced writer whose expertise lies in home improvements and renewables, as well as technology, where he is especially interested in the world of machine learning and AI. He has written for Vested, Age Times, and the Royal Mint.

For the Independent Advisor, Sam writes about windows and solar panels.

Molly Dyson

Editor

After growing up with a passion for writing, Molly studied journalism and creative writing at university in her home country of the United States.

She has written for a variety of print and online publications, from small town newspapers to international magazines. Most of her 10-year career since relocating to the UK has been spent in business journalism, writing and editing for admin professionals at PA Life magazine and business travel managers at Business Travel News Europe and representing those titles at conferences around the world.

Now an Editor at the Independent Advisor, Molly is an expert in a broad range of consumer topics, that include solar panels and renewables, home improvements and home insurance, and consumer technology such as home security and VPNs.

In her free time, Molly can usually be found exploring the outdoors with her husband and their young son or gardening.